A nonaqueous battery comprises an active material that can easily react with water (e.g., light metal or its alloy or material capable of intercalating/deintercalating lithium ion) as a negative electrode. Therefore, the nonaqueous battery is arranged such that no water is incorporated in the electrolyte, and the battery container is hermetically sealed to prevent water from entering the battery. The battery container consists of metallic members such as a can, cap and sealing plate and a resin gasket. As materials for these metallic members, the following materials have been proposed.
As the material for a cylindrical battery container, which also serves as a negative electrode terminal (can), a nickel-plated iron plate has been proposed (as disclosed in JP-A-1-279578) (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). Aluminum has been proposed as the material for a sealing plate which also serves as a positive electrode terminal (as disclosed in JP-A-1-279578). As the material for a sealing plate for a coin-shaped battery, which also serves as a negative electrode terminal, steel comprising 1 to 3% by weight of molybdenum and 15 to 18% by weight of chromium (corresponding to SUS 444 (JIS G 4305), as disclosed in JP-A-2-174078), iron (as disclosed in JP-B-61-17335) (the term "JP-B" as used herein means an "examined Japanese patent publication"), aluminum (as disclosed in JP-A-58-154163), austenite stainless steel (as disclosed in JP-A-58-157050 and JP-A-61-232555), copper (as disclosed in JP-A-61-245462), binary austenite ferrite stainless steel (as disclosed in JP-A-61-285653), ferrite stainless steel (as disclosed in JP-A-63-124358 and JP-A-2-126554) or the like have been proposed.
A nonaqueous battery comprising an active material of light metal or its alloy or an active material capable of intercalating/deintercalating lithium ion as a negative electrode exhibits a higher battery voltage than conventional aqueous batteries. For example, in an aqueous system, an alkali battery, a nickel-cadmium battery and a lead storage battery exhibit a battery voltage of 1.5 volt, 1.2 volt and 1.2 volt, respectively. On the other hand, in the nonaqueous system, a lithium carbon fluoride battery, a lithium cobalt oxide positive electrode-carbon negative electrode lithium ion battery, a polyaniline derivative positive electrode battery, a LiCoO.sub.2 positive electrode/lithium-containing transition metal oxide (e.g., Li.sub.p Co.sub.q V.sub.1-q O.sub.r in which p=0.7 to 3, q=0 to 1, and r=1.2 to 5.5) negative electrode battery exhibit a battery voltage of 3 volt, 3.6 volt, 3.8 volt and 3 volt, respectively.
If aluminum, nickel-plated iron plate, SUS 304 or SUS 430 (JIS G 4305) is used as a container material for a nonaqueous battery to prepare a sealing plate, some problems occur. In particular, a battery comprising a sealing plate made of aluminum is disadvantageous in that the sealing plate lacks mechanical strength (rigidity) and the sealing plate exhibits gradual deformation by an elastic material which is used as a safety valve, if the elastic material is embedded in the sealing plate. Further, the sealing plate can be easily deformed by a rise in internal pressure. Moreover, the sealing plate can be easily deformed upon impact if the battery should fall. A battery comprising a sealing plate made of a nickel-plated iron plate suffers from remarkable corrosion of the sealing plate during storage. A battery comprising a sealing plate made of SUS 304 or SUS 430 shows many corrosion holes in the sealing plate during storage.
A cylindrical battery container (can), which also serves as a negative electrode terminal, is less subject to corrosion than the foregoing sealing plate. In general, the cylindrical battery container is electrically connected to the negative electrode and is therefore considered to lower the corrosion potential. This is the reason why the cylindrical battery is insusceptible to corrosion. However, if the battery is overdischarged, the cylindrical battery container may corrode. If a battery comprising a cylindrical battery container made of a nickel-plated iron plate is overdischarged, remarkable corrosion occurs. Further, if a battery comprising a cylindrical battery container (can) made of SUS 304 is overdischarged, many corrosion holes occur on the inner wall of the battery container.
If such corrosion in these members is allowed to continue, the metal corroded away from the material of these membranes is deposited on the surface of the active material, which deteriorates battery performance. Further, if the corrosion continues, the container develops holes and fails to maintain its hermetic sealing structure which causes liquid leakage or battery deterioration.
As a solution to these problems, a battery comprising a negative electrode sealing plate made of a steel comprising 1 to 3% by weight of molybdenum and 15 to 18% by weight of chromium (corresponding to SUS 444) as disclosed in JP-A-2-174078 has been proposed. This steel is resistant to such corrosion. However, this steel leaves much to be desired in workability.